Deployment of the encapsulation/dehydration protocol to cryopreserve diverse microalgae held at the Institute of Soil Biology, Academy of Sciences of the Czech Republic

Twenty-seven strains of soil algae isolated from highly diverse provenances and habitats were assessed for their capacity to withstand cryopreservation using encapsulation/dehydration. Survival was assessed following the release of algae from alginate beads treated with sodium hexametaphosphate and regrowth was assessed using NAJA^® Image Analysis. Regrowth occurred in 19 strains, with >50% survival being observed in 15. Algal tolerance to osmotic dehydration and evaporative desiccation was critical to the success of the method. Recovery in five out of the remaining eight recalcitrant strains was enhanced by substituting sorbitol for the osmotic pretreatment or by combining encapsulation with two-step controlled rate cooling.